Defibrillator Working Principle
A defibrillator is a device that delivers an electric shock to the heart in order to restore its normal rhythm. The word “defibrillator” is derived from the words “defibrillate” and “defibrillator”.
A defibrillator is used when an abnormal heart rhythm develops. When this happens, the heart can no longer pump blood efficiently or effectively throughout the body. A defibrillator provides an electrical shock to this area of the heart and restores its normal rhythm.
Defibrillation is the process of restoring a normal heartbeat by using high-energy shocks. To achieve this defibrillators must be able to deliver a current that is large enough to silence all the heart muscle cells.
In order to do this, defibrillators need to have something that can collect a low flow of electricity from batteries or wall power and then discharge it in a short sharp burst as a huge amount of current. This is called a capacitor.
The Capacitor
The capacitor is an important part of the working principle in a defibrillator because it stores the low flow of current and releases it when needed. The capacitor also prevents it from discharging completely, as this would be dangerous to the patient during the defibrillation process.
A capacitor consists of two parallel metal plates separated by an electrical insulator material called the dielectric. The dielectric can be air, waxed paper, mica, ceramic, plastic or even a liquid gel (as used in electrolytic capacitors).
When electricity is applied across a capacitor the positive charge accumulates on one plate while a negative charge collects on the other plate. This is because the capacitor’s dielectric material blocks or diverts DC voltage and allows AC to pass through it. This is why a capacitor is often found in circuits to smooth out power supply output or to support frequencies such as radios.
The Battery
Defibrillators use batteries to power their electrical circuits. This is because a defibrillator needs to be portable, so it must be able to use batteries to provide the required large current.
When a battery is charged, it produces electrons that are distributed around the cell through chemical reactions between the anode and electrolyte. At the cathode, another chemical reaction occurs simultaneously that enables it to accept the electrons produced by the anode.
Each of these reactions is called a “potential.” The higher the potential, the more work that can be done by the battery.
Batteries generally have a high energy density, which means that they can be very small and still produce a large amount of energy. This is an important feature because it ensures that a battery pack is lightweight and compact, making it ideal for portable devices like defibrillators.
The Electrodes
Electrodes play a crucial role in the defibrillator working principle because they collect information about the patient’s heart rhythm and deliver energy if the device determines that a shock is necessary. They come in many forms, including hand-held paddles, internal paddles and self-adhesive disposable electrodes.
The response of a single cell to an electric field is complex and depends on many factors, such as membrane depolarization, electroporation, and collagenous septae. Various tissue structures and extracellular space limitations can also affect the outcome of a shock.
Defibrillation devices must also account for the fact that electric fields excite DVm (dissipative virtual microvolts) at sites far from the shocking electrodes. These regions are called secondary sources or virtual electrodes and may be responsible for triggering fibrillation after the shock.
Electrical and optical mapping techniques, histology, and computer modeling have all helped to provide insights into these mechanisms. However, there remains much to learn about the mechanisms that govern whole-heart defibrillation.
The Circuit
The circuit is the part of a defibrillator that collects the continuous low flow of current from batteries or wall power, stores it and then releases it as the brief large current needed for defibrillation.
Defibrillators have many different components, including a power source, variable transformer, rectifier, capacitor, switches and paddles. Some also include a display screen for trained rescuers to check de heart rhythm and a discharge button that allows healthcare professionals to manually deliver a shock independently of prompts.
The circuit in a defibrillator is made up of two parallel metal plates (shown as blue and pink squares) separated by an insulator (shown as green). Wires are connected to each plate.
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